Artificial thread and process of



Patented Dec. 3, 1935 UNITED STATES PATENT OFFICE ARTIFICIAL THREAD AND PROCESS OF PRODUCING SAME No Drawing. Application August 19, 1930, Serial No. 476,434. In Germany September 23, 1929 6 Claims.

This invention relates to artificial thread and more particularly to a process of producing artificial thread having a dull or diminished luster.

Prior to this invention, artificial thread having a mat appearance was produced by the wet spinning process by adding opaque substances to the spinning solution or precipitating said substances in the spinning solution. According to other procedures, the opaque substances were formed 10 by spinning a solution containing a substance which reacted with the coagulating bath as it was spun therein.

Processes have also been devised for diminishing the luster of dry spun artificial thread by more or less completely dulling the thread. For instance, it had been proposed to first immerse the finished thread, or fabrics produced therefrom, in a solution of sodium sulphate or sulphuric acid and then in a barium chloride bath,

whereby barium sulphate was precipitated on the surface of the thread. However, the precipitate resulting from this treatment was irregular and, since it was formed only on the surface of the thread, only loosely adhered thereto. To overcome these difficulties it has been further proposed to produce a water-insoluble substance by double decomposition, either directly in the acetyl cellulose or in the spinning solution. The insoluble precipitates produced in this manner must be so fine that they will not clog the spinneret during spinning. In general, this is rather difficult to attain, and when such spinning solutions are spun, the insoluble precipitates are often retained by the filters and the spinnerets clogged.

It had also been proposed to disperse in a finely divided condition solid substances, such as magnesium oxide, insoluble soaps, etc., in the spinning solution. However, such processes required extensive apparatus and furthermore had the dis-- advantages of the previously-described process to even a greater extent.

We have found that artificial thread, particularly that produced from cellulose derivatives, such as acetyl cellulose, can be delustered and 45 the above-mentioned disadvantages overcome or avoided by introducing into the spinning solution a substance, such as an acid or an anhydride, which is soluble in the solvent used, dry spinning said solution, and subjecting the dry finished 50 thread to a bath containing a substance which reacts with the first-mentioned substance to form an insoluble or difiicultly soluble compound.

It is therefore an object of this invention to provide a method of producing a delustered. arti- 55 ficial thread, particularly one formed of a cellulose derivative, and specifically of cellulose acetate.

Another object of this invention is to provide a method of delustering artificial silk formed of a cellulose derivative, such as cellulose acetate, 5"

which consists in dry spinning a solution containing a substance, such as an acid or anhydride, and subjecting the dry finished thread to a bath containing a substance which reacts With the first-mentioned substance to form a substantially l0 insoluble compound.

A further object of this invention is to provide a method which comprises spinning a. solution containing a cellulose derivative, such as cellulose acetate, and an acid, such as stearic, and sub- 15 jecting the finished thread to a solution containing a salt, such as barium chloride, whereby an insoluble stearate, such as barium stearate, is produced in the thread.

According to this invention small quantities of 20 inorganic or organic (aliphatic or cyclic) acids or acid anhydrides which are soluble in the solvent are dissolved in the spinning solution, for instance, a solution of a cellulose derivative, such as cellulose acetate in an acetone alcohol mix- 25 ture. This solution is dry spun in the usual manner, and the dry finished lustrous thread is subsequently treated with an aqueous solution of such substances, as salts or other compounds, which react with the acid or anhydride to form 30 a substantially insoluble compound. Obviously, the acids or anhydrides contemplated are not volatile.

It is obvious that many acids, both organic and inorganic or anhydrides may be employed in 35 this process. As examples of specific materials of the above referred to classes, boric acid, higher fatty acids, and benzoic anhydride may be mentioned.

The quantity of acid or anhydride used should preferably be such that without subsequent treatment the thread produced at the end of the dry spinning operation is not delustered. The quantitles of the substance added should, furthermore, be such that the tenacity and other desirable physical properties of the thread are not influenced thereby. In filtering and spinning, the clear solution does not behave differently from normal or usual spinning solutions. The acid or anhydride may be incorporated in the spinning solution in a number of ways. For instance, it may be dissolved in the solvent prior to dissolving the cellulose derivative therein. Or, it may be mixed with the cellulose acetate and the mixture dissolved to form the solution. If desired, the cellulose acetate solution may be produced in the usual manner and the acid or anhydride subsequently dissolved therein.

For the subsequent treatment, aqueous solutions of salts or compounds of the heavy or alkaline earth metals, including aluminum, magnesium, and zinc, may be used. In carrying out the subsequent treatment, the thread is immersed for any suitable length of time in the form of skeins or fabrics in the treating bath at any suitable temperature, preferably between room temperature and about 50 C. Higher temperatures, though they may be used, are not essential for the successful practice of the invention.

By suitable choice of the acid and anhydride and proportions thereof, as well as the nature and concentration of the subsequent treating bath, the degree of delustering may be controlled.

It is to be noted that at the end of the spinning operation, the thread is of normal luster and is capable of being used in that condition. When a thread of reduced luster is desired, then the normal lustrous thread is treated as previously described. Obviously, the delustering may be accomplished while the thread is in skein form or after it has been manufactured into a fabric.

To more clearly explain the invention, the following specific' example illustrating one modification is set forth. It is, of course, to be understood that the invention is not restricted to this specific modification.

Example-20 kgs. acetyl cellulose are stirred in kgs. acetone in which grams of stearic acid are dissolved until the solution is clear. This solution is dry spun in the usual manner, and the acetate thread produced has a normal luster.

The thread in the form of skeins is immersed for several hours in a 1% barium chloride bath and then washed and dried. The thread resulting from this treatment has a subdued luster.

Since it is obvious that various changes may be made in the specific details herein set forth, the invention is not restricted thereto, except as set forth in the appended claims.

We claim:

l. A- process which comprises dry spinning a solution of a cellulose derivative containing a substance of the class which consists of normally non-volatile organic acids and organic acid anhydrides dissolved therein to form a thread of normal luster, said thread being capable of use as a lustrous thread, and subsequently subjecting the lustrous thread to a solution of a substance which reacts with the first-named substance to form a substantially insoluble compound, whereby the luster of the thread is reduced.

2. A process which comprises dry spinning a solution of a cellulose derivative containing an organic acid anhydride dissolved therein to form a thread of normal luster, said thread being capable of use as a lustrous thread, and subsequently subjecting the lustrous thread to a solution of a substance which reacts with said anhydride to form a substantially insoluble compound, whereby the luster of the thread is reduced.

3. A process which comprises dry spinning a solution of a cellulose derivative containing a normally nonvolatile organic acid dissolved therein to form a thread of normal luster, said thread being capable of use as a lustrous thread, and subsequently subjecting the lustrous thread to a solution of a substance which reacts with said acid to form a substantially insoluble compound, whereby the luster of the thread is reduced.

e. A process which comprises dry spinning a cellulose derivative solution having stearic acid dissolved therein to form a thread of normal luster which is capable of being used as a 1ustrous thread, and subsequently at any desired time subjecting the finished lustrous thread to a.

solution of' a substance which reacts with said stearic acid to form a substantially insoluble compound, whereby the luster of the thread is reduced.

5. A process which comprises dry spinning a cellulose derivative solution having stearic acid dissolved therein to form a thread of normal luster which is capable of being used as a lustrous thread, and subsequently at any desired time subjecting the finished lustrous thread to an aqueous solution of barium chloride, whereby the luster of the thread is reduced.

6. A process which comprises dry spinning a solution of a cellulose derivative containing henzoic anhydride dissolved therein to form a thread HANS ALTWEGG. ARMIN EICHLER. 

